Ambisonics is fascinating.
It builds directly on what Blumlein was doing with mid-sides arrays in the 1930s and, had he survived the War, I'm reasonably confident that he would have developed Ambisonics himself as it is such a logical extension.
As it was, it took Gerzon and Craven to do it in the 70s, but even then the analogue matrixing technology could barely keep up. That lead inevitably to those early SoundField mics having a (deserved) poor reputation for noise, and so limited their adoption quite considerably. They were more of a curiosity than a valid recording tool for most....
Calrec (who manufactured the original SoundField mics) was bought out by AMS in 1987. At that time AMS were leading proponents of digital audio, making reverbs and delay lines, and then the ground-breaking Audiofile DAW). They wanted a digital console to partner the Audiofile and so in 1987 they bought out Calrec who had been developing one.
Under this new ownership, the Soundfield mic was continued, and Ken Farrer (Former Calrec Director) designed the SoundField Mk5 and the SPS422 for them on a consultancy basis). However, once AMS has finished asset-stripping Calrec for its innovative digital sound console designs they had no interest in the rest of the former Calrec's products.
So, some of the original Calrec directors bought back the remnants of the analogue broadcast console business and re-established the independent Calrec brand (but were banned from developing digital consoles for a decade), while their original digital console design became the AMS Logic 1.
AMS subsequently bought out Neve, and then Siemens bought the whole thing, and the AMS brand is largely forgotten now.
Fortunately, though, some people could see the potential of the Soundfield mic and there was sufficient commercial interest for Ken Giles to acquire the technology from AMS in 1993 and relaunch it as the independent SoundField company which he ran alongside his other Drawmer Distribution business. It was under his stewardship that the mic was developed further, and the implementation of digital signal processing for the Ambisonic decoding at the turn of the century really allowed the true potential of the SoundField mic to be revealed. He also bought in help to make major improvements to the microphone's electronics to improve the fidelity and noise performance , and to redesign the portable version from the clunky AMS ST250 to the SoundField ST350 and now the ST450 mkii -- which is a phenomenal mic.
However, it's the current popularity of VR/AR that has created the huge demand for ambisonic technology, and hence the growth in other companies providing products and development of the format.
Ambisonics may well remain something of a specialist niche thing, but these newer low-cost ambisonic mics partnered with low-cost decoder plugins has really made the format far more affordable to those with a casual interest as well as the longstanding enthusiasts.